Red blood cells impenetrable to malaria parasite

For people carrying a mutation that causes the rare genetic disease – pyruvate kinase deficiency – it’s not all bad news. The mutation also protects against malaria.

About one in 20,000 people have two copies of a genetic mutation that prevents red blood cells from producing energy and causes anaemia. Patients with the condition often die young.

But people with one mutated pyruvate kinase (PK) gene might be spared from the malaria parasite Plasmodium falciparum, says Philippe Gros, a geneticist at McGill University in Montreal who led the new study. “These guys are absolutely normal; they don’t know that they have one copy of the mutation,” he says.

Offering resistance

Gros’ team is now collecting blood samples in areas rife with malaria to determine whether the mutation offers some resistance in people with one mutation. “In one or two years max we’ll have the answer,” he says.

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About 300 million people contract malaria each year, and one million die.

Another disease, sickle cell anaemia, protects against malaria in a similar way. Patients with a single mutation in a gene for the blood protein haemoglobin have partial resistance to malaria, while two copies spell disease.

Easy targets

Gros and colleagues tracked down several patients and collected blood from them. When the researchers tried infecting the red blood cells with P. falciparum, the sickly cells were virtually impervious to the parasite.

Some parasites managed to invade, but those cells proved easier targets for the immune system. White blood cells destroyed the infected cells in a Petri dish.

Gros’ team performed the same tests in cells of people who had only one mutation in the PK gene. Their red blood cells easily succumbed to the malaria parasite. However, white blood cells made easy work of the infected cells. This suggests that people with PK mutations – but no disease – might get some protection from malaria, Gros says.

That condition would be hard to mimic with a drug, says Johanna Daily, an infectious disease expert at Brigham and Women’s Hospital in Boston, Massachusetts. A drug that blocks PK could kill off red blood cells. “It is not change that we would want to create through drugs,” she says.